1. Field of the Invention
The present invention relates to an actuator drive control device for an active vibration isolation support system for controlling an operation of an actuator to suppress transmission of vibration from an engine having a plurality of banks.
2. Description of the Related Art
Such an active vibration support isolation system is known from Japanese Patent Application Laid-open No. 7-42783.
This active vibration isolation support system changes a spring constant by applying electrical current to an actuator so as to vibrate a movable member. The relationship between the phase and peak electrical current value of the applied electrical current that sets the spring constant is stored as a map in advance, and the phase and the peak electrical current value of the electrical current to be applied to the actuator are obtained from the map according to the rotational speed of the engine, thereby allowing the active vibration isolation support system to exhibit an effective vibration isolation function in various regions of the rotational speed of the engine.
The conventional active vibration isolation support system estimates the vibration state of the engine in each operation period of each cylinder, and based on this vibration state, the active vibration isolation support system controls the operation of the actuator in the operation period of the next cylinder. Therefore, in a V-type engine having a front bank and a rear bank, based on the vibration state estimated in the operation period of the cylinder in the front bank, the active vibration isolation support system controls the operation of the actuator in the subsequent operation period of the cylinder in the rear bank, or based on the vibration stage estimated in the operation period of the cylinder in the rear bank, the active vibration isolation support system controls the operation of the actuator in the subsequent operation period of the cylinder in the front bank.
In this case, if the vibration state due to the operation of the cylinder in the front bank and the vibration state due to the operation of the cylinder in the rear bank are the same, there is no problem, but when the vibration states differ significantly, there occurs a deviation between the actual vibration state of the engine and the control of the actuator to isolate the vibration, leading to a possibility that the active vibration isolation support system cannot exhibit an effective vibration isolation function.
For example, as shown in FIG. 9A, the vibration waveform by the operation of the front bank should theoretically be completely in opposite phase from the vibration waveform by the operation of the rear bank, but as shown in FIG. 9B, the vibration waveforms are not completely in opposite phase from each other, and a phase shift occurs, because the banks of the engine do not actually have completely symmetrical structures. Accordingly, when control of the actuator in the operation period of one bank is performed based on the vibration state of the other bank of the front bank and rear bank, there arises a possibility that the active vibration isolation support system performs an inappropriate operation.